Production costs are being reduced by automation, robotics, computer-integrated manufacturing, cost reduction studies and more. These new technologies are expensive to buy, repair, and maintain. Hence, the demand on maintenance is growing and its costs are escalating. This new environment is compelling industrial maintenance organizations to make the transition from fixing broken machines to higher-level business units for securing production capacity. On the academic front, research in the area of maintenance management and engineering is receiving tremendous interest from researchers. Many papers have appeared in the literature dealing with the modelling and solution of maintenance problems using operations research (OR) and management science (MS) techniques and this area represents an opportunity for making significant contributions by the OR and MS communities. This text provides developments in the area of maintenance modelling. The book is intended to serve as an informative introduction to this field that may permit additional developments and useful directions for more research in this fast-growing area. The book is divided into six parts and contains 17 chapters. Each chapter has been subject to review by at least two experts in the area of maintenance modelling and optimization.